<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="../react18/react.development.js"></script>
  <script src="../react18/react-dom.development.js"></script>
  <script src="../react18/babel.min.js"></script>
  <script src="../react18/prop-types.js"></script>
</head>

<body>
  <div id="app"></div>
  <script type="text/babel">
    /* 
      回调形式的refs
         ref 属性，你会传递一个函数。这个函数在渲染的时候就会执行,这个函数中接受 HTML DOM 元素作为参数，以使它们能在其他地方被存储和访问
    */
    /* class Parent extends React.Component{
      render(){
        return (
          <div>
            <input type="text" ref={c=> this.iptEle = c }/>
            <button onClick={this.handle}>点我弹出用户的输入内容</button>
          </div>
        )
      }

      handle = () => {
        const {value} = this.iptEle;
        alert(value)
      }
    }

    const root = ReactDOM.createRoot(document.getElementById('app'));
    root.render(<Parent/>) */


    class App extends React.Component{
      render(){
        return (
          <div>
            <input type="text" ref = { c => this.oIpt = c }/>
            <button onClick={this.handle}>点我弹出用户的输入内容</button>
          </div>
        )
      }

      handle = () => {
        // console.log(this.oIpt);
        const {value} = this.oIpt
        alert(value)
      }

    }

    const root = ReactDOM.createRoot(document.getElementById('app'))
    root.render(<App/>)




  </script>
</body>

</html>